Hydraulic brake



W. F. OLIVER HYDRAULIC BRAKE Dec. 22, 1936.

2 Sheets-Sheet 1' Filed June 6, 1932 lllhml.

Dc. 22, 1936. w F. OUVER 2,065,017 Y l HYDRAULIC BRAKE y v Filed June 6, 1932 2 Sheets-Sheet 2 Patented Dec. 22,. 1936 UNITED STATES PATENT OFFICE 2,065,017 HYDRAULIC BRAKE Wallace F. Oliver, Detroit, Mich., assignor to Hydraulic Brake Company, Detroit, Mich., a corporation of California Application June 6, 1932, Serial No. 615,651 3 Claims. (Cl. 18S-3) My invention pertains to hydraulic brakes and Fig. 5 is an enlarged sectional view of the mechis particularly concerned with the provision of anism shown in Fig. 3; and a hydraulic brake especially adapted for use on Fig. 6 is a sectional view of a detail of the automotive vehicles of the tractor and trailer coupling means. 5 type. In present trucking practice it is com- In the drawings, I have indicated a conven- 5 mon to provide a tractor vehicle which is utilized tional automobile truck IIJ as the tractor vehicle, to haul one or more trailer vehicles which are and this truck is connected by a pin and link readily attachable to and detachable from the connection with a trailer I2. The truck is tractor vehicle. One of the important problems provided with the usual brake pedal I3 pivoted 10 arising from the use of such tractor and trailer at I l to the frame of the vehicle and provided 10 vehicles lies in the provision of adequate braking with an arm I5 attached to a link I6 for actuatmechanism whereby brakes located at the wheels ing lever |'I splined to oscillable shaft I8.

'of the trailer vehicles may be -accurately and sat- The shaft I8 extends into a housing I9 which isfactorily controlled by the operator of the tracserves as a nuid reservoir and which contains a i5 tor vehicle. compression cylinder 20 having a piston 2| re- 15 An object of-my invention is to provide a hyciprocated by arm 22 likewise splined to the draulic brake system which will permit the driver shaft I8. The reservoir I9, cylinder and atof the tractor vehicle to control accurately and tendant mechanism, constitute the reservoir and efficiently the brakes on one'or more trailer vemaster cylinder unit of a hydraulic brake system. o hicles connected with the tractor vehicle. The piston 2| is provided with diagonal ducts Another object is to provide a novel means v8|) which are closed during forward movement for coupling the braking mechanism of the trailof the piston by a' rubber cup 8| held against the er vehicle with that of the tractor vehicle. face of the piston by a metal cup 32 acted upon Another object is to provide means for posiby the piston return spring 83. v'I'he otherend tively sealing the fluid conduits on the several of the spring 83 rests upon the return valve 25 vehicles when the braking systems of the vehimember 84 of a two-way check Valve which cles are disconnected from each other. includes an outlet valve 85 normally maintained Another object is to provide inexpensive and in closed positionby a light spring 86. In the effective means for 'locking the brakes of the rest position of the parts, the interior of the trailer vehicle when such vehicle is disconnected cylinder 20 is in open communication with the o from the tractor vehicle. reservoir through cylinder port B'I and openings Another object is to provide simple and eiec- 83 in the metal cup 82. The interior of the restive means for maintaining the uid in the brake ervoir communicates with atmosphere by Way of mechanism of the tractor and trailer vehicles two-way valve 89 located in the filling opening. 35 under pressure prior to an uncoupling opera- The discharge end of the compression cylinder 35 tion. 20 communicates with conduits 23 and 24 leading Another object is to provide a coupling means to cylinders 25 located at the vehicle wheels. for the conduits of tractor and trailer vehicles These wheel cylinders may be of the type shown which may be connected and disconnected within my Patent No. 1,832,135, issued November 17,

40 out the loss of fluid therefrom. 1931, and actuate brake shoes 26 pivoted at 21 40 Other objects and advantages will become apon a supporting pan 28 supported on the vehicle parent as the description proceeds. axle. The brake shoes 26 are returned to re- Fig. 1 is an elevation, partially in section, showtracted position by spring -29. ing a tractor and trailer in coupled relation and In the present instance, the foot pedal pressure emphasizing the braking mechanism ofthe two is augmented by a vacuum booster comprising a 4 vehicles; vacuum cylinder 30 connected to the intake mani- Fig. 2 is a diagramm-atic view of the braking fold 3| by a conduit 32 having an interposed valve mechanism of the vehicles shown in Fig. l; 33 controlled by the position ofthe foot pedal I3.

Fig. 2a is a detailed sectional view through a The vacuum cylinder has a piston 34 connected preferred type of master cylinder and reservoir to the link I6.

unit. The discharge end of the compression cylinder Fig. 3 is an elevation of the coupling means 20 also communicates with a conduit 35 having for the brake mechanisms of the two vehicles; a flexible section 35 leading to a coupling mem- Fig. 4 is a plan view of one of the elements of ber 31 mounted on a pin 38 which is rotatable the coupling mechanism shown in Fig. 3; and vertically slidable in bracket 39 lsecured to 55 ly described as used on feo 4i supported by bracket 42 attached to the trailer frame.

The pin 4l is preferably coaxial with the pin of the coupling means Il. The coupling member 40 is connected to the exible portion 43 of a conduit 44 having branches leading to wheel cylinders 45 which may be identical with the Wheel cylinders125 on the truck. The brake shoes and attendant mechanism actuated by the wheel cylinders 45 may be identical with that previousthe truck lli. While Figure 2 shows only two of the trailer wheel brake assemblies, it isto be understood that the trailer shown in the' drawings has four wheels, each of which is provided with a brake assembly.

Referring particularly to Figs. 3 to 6, inclusive, it is' apparent that the coupling member 31 includes a cylinder' 46 in open communication with the exible conduit portion 35. The cylinderv 45 is closed at one end by a head 41 secured to the cylinder 45 by suitable bolts 48. The other end of the cylinder 45 is provided with a valve seat d5 adapted to be closed by a valve 55 when. the tractor and trailer are disconnected.

The valve 55 has a valve stem 5ll threadedly engaging a reduced extension 52 of the head 41 and is provided with a hand wheel 53 for opening l and closing the valve. A packing 54 and gland the valve stem 5i.

nut 55 are provided to prevent leakage around The cylinder 45 y for retaining coupling sleeve 51 which is adapted to be threadedly engaged with the cylinder 58 of the complementary coupling member when'the parts are in coupled relation. The cylinder 58 is provided with a head 55, valve seat iid,v valve 5l, valve stem 52, and hand wheel 63 substantially identical with those described in connection with cylinder 45. The contacting faces of cylinders 45 and-58 are provided with sealing rings 6d which are preferably of lead or similar material suitable for forming a leak-proof seal therebetween.`

With theparts in coupled relation and the valves 5i) and 6! in open position, as indicated, in

Figs. 2 and 5, the conduit 44 o f the trailer vehicle' is in free communication'with conduits 23 and 24 and the discharge end of the compression cylinder ,25, so .that operation of the foot-pedal l5 will apply the brakes on both the tractor and trailer vehicles. If it be desired to disconnectithe trailer from the tractor and ,leave the brakes of the trailer in set positon, the driver rst depresses the foot-pedal l5 until the desired pressure is created on the brakes of the tractor and trailer vehicles, whereupon the driver uses his other foot to move the slide 65 into engagement with one of the teeth 66 on the foot-pedal I3, thereby lock'- ing the foot-pedal against the action ofthe return spring 61, and holding the brake systems of the tractor and trailer under pressure.' The driver then descends `from and rotates the hand wheels 53 and 63 to close the valves 50 and 5l.

The valve 8i is provided with a compressibl'e gasket 68 of cork or other suitable material, which -completely lls the very small space between the opposed ends of the valves, thereby'preventing the presence of any liquid between the ends of thecouplin'g members 31 `and 40 when they are uncoupled, and thus avoiding any possibility of.

' tion.

loss of uid as a result of the uncoupling operaf brake on the tractor v 11, thereby permitting is provided with a ange 55 y y piston 15 and lock it 'indicated by the reference thereby displacing the cab of the truck may be moved to positions covering the ends of'l the coupling members, thereby protecting these ends from dirt and corrosion. The covers 59 and 1G are carried by rods 1l slidably mounted in pivot pins 12 and held in selected positions by springs 13.

After the driver has disconnected the coupling members 31 and 40, he may withdraw the pin of the pin and slot connection Il, release the by withdrawing the slide 65, and move the tractor away under its own power,.leaving the trailer in any desired location with its brake set so that it cannot move therefrom.

Under some conditions it may be desired to move the trailer from place to place without rst connecting it to a tractor vehicle, and under such conditions it will be necessary to provide means for releasing the brakes on the trailer to permit such movement. For this purpose I have provided the brake mechanism of the 'trailer with a cylinder 1d having a piston 15 normally v'maintained in its advanced position by a hand brake lever 16 having the usual ratchet mechanism 11.

When it is desired to move the trailer, it is only necessary to release the ratchet mechanism the piston 15 to move to retracted position, whereupon the brakes on the trailer are immediately released. The trailer 'mayl then be pushed from one locationv to another, and when it is again desired to set the brakes of the traler, it is only necessary tojpull back on the hand brake lever 15 to advance the in such advanced position.

The cylinder 1d is preferably provided with a filling opening and removable cover therefor, -character 15 in Fig.

2 of the drawings.

In' the normal operation of the truck and trailer assembly a depression of the foot pedal i3 will advance the master cylinder piston 2i,

der 25 and actuating the motor cylinders 25 l on the tractor and motor cylinders 55 on the trailer to cause these motor cylinders to apply the brake shoes connected therewith. When the driver withdraws his foot from thepedal l5, this pedal is immediately returned to retracted position by spring 61. The piston operating arm 22 returns with the foot pedal i3 and permits spring 83 to return master cylinder piston 2i.

Spring 83 returns the master cylinder piston 2l faster than the master cylinder 20 by the return of the motor cylinder pistons under the inuence of the retractile springs fluid from the master cylinuid can be returned to the associated with the brake shoes.

This results in the creation of suction in the master cylinder which draws fluid from the reservoir through ducts 80 in the piston and past vcollapsed rubber cup 8l. In the rare instances in which leakage has occurred during the operation of the brakes, the fluid thus drawn into the master cylinder compensates for such leakage.

Normally, no such leakage occurs, and the iluid thus drawn past the master cylinder piston during its return stroke, constitutes an excess which is returned to the reservoir through the port 81 as the wheel cylinder `pistons are completely retracted by the retractile springs atgg l tains the conduits and wheel tached to the brake shoes. Any small bubbles of air which may have found their way into the motor cylinders or conduits are returned to the master cylinder by the returning fluid upon the completion of each-braking operation. From the master cylinder these minute bubbles of air are carried to the reservoir by the excess fluid returned thereto and thus the system is continually maintained free of air bubbles and completely illled with Van incompressibleliquid. It is to be noted that the two-way valve 84 normally maincylinders under a superatmospheric pressure which inhibits the leakage of atmospheric air into the conduits and wheel cylinders.

A further feature of my invention lies in the 'provisions for compensating for volumetric changes in the uid contents of the conduits and wheel cylinders of both the truck and trailer. In the event oi a sudden decrease in atmospheric temperature, the resultant volumetric contraction of the fluid in the wheel cylinders and conduits of the truck and trailer will draw additional uid from the reservoir through port 81 and past outlet valve 85 to maintain the conduits and wheel cylinders completely lled at all times. Conversely, a rise in atmospheric temperat'ure, accompanied by a volumetric increase in the uid contained in the wheel cylinders and conduits of the truck and trailer, will return iiuid to the master cylinder and reservoir past inlet valve 84 and through port 81, whereby dragging of the brakes is prevented.

The coupling means illustrated and described herein is claimed in my divisional application, Serial No. 733,221, led June 30, 1934.

While I have illustrated and described a preferred embodiment of my invention, it is to be understood that my invention is capable of numerous adaptations and. that the scope of my invention is limited solely by the following claims.

I claim:

l. In a, hydraulic brake system of the class described, the combination of a compressor having a piston therein, a rst conduit system connected to said compressor, a motorconnected to said conduit system and actuated by liquid pressure created therein by said compressor, a brake element operated by said motor, a second conduit system, a motor connected to said second conduit system and actuated by liquid pressure created therein, a brake element operated by said last named motor, said motors designed for complete operation by a single stroke of said piston, detachable coupling means whereby said conduit systems may be connected in liquid transferring relationship and thereafter disconnected and sealed from atmosphere without admission of air to either conduit system, means provided by said compressor for maintaining all ofv said conduit systems and motors free 'of entrapped air, and means for operating said compressor.

2. In a hydraulic brake system of the class described, the combination of a compressor having a piston therein, a rst conduit system connected to said compressor, motors connected to said conduit system and actuated by liquid pressure created therein by said compressor, brake elements operated by said motors, a second conduit system, motors connected to said second conduit system and actuated by liquid pressure created therein, brake elements operated by said last-named motors, all of said motors designed for complete operation by a single stroke of said piston, detachable coupling means whereby said conduit systems may be connected in liquid transferring relationship and thereafter disconnected and sealed from atmosphere without admission of air to or leakage of liquid from either conduit system, means provided by said compressor for compensating for volumetric changes in the liquid contained in said motors and conduit systems and for maintaining all of said motors and conduit systems free of entrapped air, and operating means for said compressor.

3. In a hydraulic brake system of the class described, the combination of a compressor having a piston therein, a first conduit system connected to said compressor, motors connected to said conduit system and actuated by liquid pressure created therein by said compressor, brake elements operated by said motors, a second conduit system, motors connected to said second conduit system and actuated by liquid pressure created therein, brake elements operated by said -last-named motors, all of said motors designed for complete operation by a single stroke of said piston, detachable coupling means whereby said conduit systems may be connected in liquid transferring relationship and thereafter disconnected and sealed from atmosphere without admission of air to or leakage of liquid from either conduit system, means provided by said compressor for compensating for volumetric changes in the liquid contained in said motors and conduit systems and for maintaining all of said motors and conduit systems free of entrapped air, means for operating said compressor, and a second compressor connected to said second conduit system for controlling the latter when disconnected from said rst conduit system.

WALLACE F. OLIVER. 

